Method and apparatus for drilling a curved bore

Claim 2

Apparatus for attachment to a rotary drill string in drilling a curved bore in a subsurface formation comprising: a drill bit; at least one articulated joint connected to the lower end of said drill string; and a reamer having a front stabilizer section interconnected for rotation between said articulated joint and said drill bit, said drill bit rigidly and directly connected to said front stabilizer section of said reamer about a common longitudinal axis therewith, said reamer including a plurality of cutting blades projecting substantially in an outward radial direction rearwardly of said front stabilizer section, said cutting blades each having an elongated cutting edge extending substantially parallel to the direction of drilling, said stabilizer section of a diameter substantially corresponding to that of said drill bit between said cutting blades and said drill bit, and said cutting blades being overgauged with respect to said drill bit and said stabilizer section.

Claim 3

Apparatus according to claim 1, said stabilizer member disposed in surrounding relation to said reamer with said cutting blades projecting radially beyond the external surface of said stabilizer member.

Claim 4

Apparatus according to claim 1, said cutting blades extending axially in spaced circumferential relation to one another, each cutting blade extending axially in a direction parallel to said longitudinal axis and terminating in elongated cutting edges at its outermost radial end surface.

Claim 5

Apparatus according to claim 3, each cutting blade having an inclined leading end portion tapering forwardly toward said drill bit from said cutting edges.

Claim 6

Apparatus according to claim 1, said stabilizer member interposed between said reamer and said drill bit and having axially extending flow channels extending in circumferentially spaced relation between said cutting blades.

Claim 7

Apparatus according to claim 5, said stabilizer member having slotted end portions in surrounding relation to said reamer with said cutting blades projecting through said slots for a limited distance beyond the external surface of said stabilizer member.

Claim 8

In apparatus for use in combination with a radial whipstock assembly wherein a drill bit is connected to the lower end of a rotary drill string for advancement along a guide surface of the whipstock in drilling a curved bore, the improvement comprising: a reamer assembly rigidly connected to and directly behind said drill bit, said reamer assembly having a front stabilizer section directly connected to said drill bit and a plurality of cutter blades of a greater effective cutting diameter than said drill bit at a trailing end of said stabilizer section, each cutter blade having a leading end portion in facing relation to said drill bit and at least one cutting edge extending rearwardly in a direction away from said drill bit and from said leading end portion.

Claim 9

In apparatus for use in combination with a radial whipstock assembly wherein a drill bit is connected to the lower end of a rotary drill string for advancement along a guide surface of the whipstock in drilling a curved bore, the improvement comprising: a reamer assembly rigidly connected to and directly behind said drill bit, said reamer assembly having a front stabilizer section directly connected to said drill bit and a plurality of cutter blades of a greater effective cutting diameter than said drill bit at a trailing end of said stabilizer section, each cutter blade having a leading end portion in facing relation to said drill bit and at least one cutting edge extending rearwardly in a direction away from said drill bit and from said leading end portion.

Claim 10

In apparatus according to claim 7, each cutter blade defined by a radial tooth covered with a hard surfacing material.

Claim 11

In apparatus according to claim 8, each reamer tooth having opposed leading and trailing end surfaces inclining toward one another and terminating in an external, squared cutting end surface portion, and said hard surfacing material applied to said external cutting edge as well as said leading and trailing end surface portions of each tooth.

Claim 12

In apparatus according to claim 7, said stabilizer section having longitudinal flow channels extending therethrough.

Claim 13

In apparatus according to claim 10, said stabilizer section having slotted end portions in surrounding relation to said reamer assembly with said cutting blades projecting through said slots for a limited distance beyond the external surface of said stabilizer member section.

Claim 14

In apparatus for use in combination with a radial whipstock assembly wherein a drill bit is connected by a flexible shaft to the lower end of a rotary drill string for advancement along a guide surface of the whipstock in drainhole drilling, the improvement comprising: a reamer assembly including a reamer body rigidly connected to and directly behind said drill bit having cutter blades of a greater effective cutting diameter than said drill bit a stabilizer section rigidly affixed to said reamer body in leading relation to said cutter blades, said stabilizer section having longitudinal flow channels extending therethrough, said cutting blades projecting through open slots in said stabilizer section for a limited distance beyond the external surface of said stabilizer section, each cutter blade defined by a radial tooth covered with a hard surfacing material, each said tooth having leading and trailing end surfaces inclining toward said reamer body and terminating in an outer radial cutting end surface portion, said hard surfacing material applied to said cutting end surface portion and said leading and trailing end surface portions.

Claim 15

In apparatus for use in combination with a radial whipstock assembly wherein a drill bit is connected by a flexible shaft to the lower end of a rotary drill string for advancement along a guide surface of the whipstock in drainhole drilling, the improvement comprising: a reamer assembly including a reamer body rigidly connected to and directly behind said drill bit having cutter blades of a greater effective cutting diameter than said drill bit a stabilizer section rigidly affixed to said reamer body in leading relation to said cutter blades, said stabilizer section having longitudinal flow channels extending therethrough, said cutting blades projecting through open slots in said stabilizer section for a limited distance beyond the external surface of said stabilizer section, each cutter blade defined by a radial tooth covered with a hard surfacing material, each said tooth having leading and trailing end surfaces inclining toward said reamer body and terminating in an outer radial cutting end surface portion, said hard surfacing material applied to said cutting end surface portion and said leading and trailing end surface portions.